Generally, there exists a variety of different multilayer assemblies and structures in the context of electronics and electronic products. The motivation behind the integration of electronics and related products may be as diverse as the related use contexts. Relatively often size savings, weight savings, material savings, cost savings, performance gain or just efficient cramming of components is sought for when the resulting solution ultimately exhibits a multilayer nature. In turn, the associated use scenarios may relate to product packages or food casings, visual design of device housings, wearable electronics, personal electronic devices, displays, detectors or sensors, vehicle interiors, antennas, labels, vehicle electronics, furniture, etc.
Multilayer structures are obtainable, for example, by utilizing a substrate, such as a circuit board or even a plastic film, which may be provided with electronics and overmolded by plastics so as to establish the multilayer structure with the electronics at least partially embedded in the molded layer. Accordingly, the electronics may be concealed from the environment and protected against environmental conditions such as moisture, physical shocks, or dust, whereas the molded layer may further have various additional uses in terms of aesthetics, transfer medium, dimensioning, etc.
Electronics such as electronic components, integrated circuits (ICs), and conductors, may be generally provided onto a substrate element by a plurality of different techniques. For example, ready-made electronics such as various surface mount devices (SMD) may be mounted on a substrate surface that ultimately forms an inner or outer interface layer of a multilayer structure.
Additionally, technologies falling under the term “printed electronics” may be applied to produce electronics directly and essentially additively to the associated substrate. The term “printed” refers in this context to various printing techniques capable of producing electronics/electrical elements from the printed matter, including but not limited to screen printing, flexography, and inkjet printing, through a substantially additive printing process. The used substrates may be flexible, which is, however, not always the case.
Electronic assemblies are used in variety of different applications. In many of these applications, sensors, switches and/or devices for monitoring and/or responding to changes in the pressure affecting them, for example pressure sensors or mechanical push buttons, are desired features, such as in many control systems or user interfaces utilizing electronics. The sensors may be based on monitoring capacitance, inductance or resistance, or based on changes in optical properties or on various other known techniques. The devices utilizing the sensors may have various forms, and be utilized for different purposes and in different environments.
One example of a technical field in which, for example, mechanical push buttons are being utilized is automotive industry. Vehicles can have a variety of electronic devices connected to the common electrical system of the vehicle. The devices are typically controlled by using devices which monitor the pressure affecting them and/or operate in response to a change in said pressure or by applying force, such as in case of mechanical push buttons. Furthermore, capacitive switches may be utilized as means for controlling a device in the vehicle. However, in those conditions capacitive non-contact electric switches are prone to error functions caused by electromagnetic interference or erroneous detection by the capacitive sensor, or system thereof, in response to a hand movement which was not intended to cause said detection or action by the capacitive sensor.
Typical mechanical push buttons can also be used, however, they tend to be large, costly and exposed to dirt, such as grease from user's fingers, and can affect adversely otherwise elegant interior surface of the vehicle. When integrating mechanical push buttons to surrounding structures, the structure is designed so that the button can be arranged and fixed to the structure and that moving of the push button in response to the pressure applied to it is made possible. Typically, this is done by having the push button or a rotatable switch separated from the surrounding structures, for example, protruding from the structure or at least having a gap enabling the movement with respect to the structure. The buttons or switches can be overlaminated or a separate protective layer can be arranged to cover them in order to protect them from dirt and to provide more uniform outer surface with respect to the surrounding structure. The overlaminate or the separate protective layer is such that it enables to use of the button or the switch, that is, it is highly flexible in order to enable the operating of the button or the switch. However, the laminate or layer can easily be damaged or worn out when used repeatedly. The laminate or the layer can easily become detached from the button or the switch, thus deteriorating the performance of the device.
There is thus still a need for developing a method for manufacturing pressure sensing switches and devices, and for devices thereof, which are less prone to interferences and operate more reliably than the known attempted solutions.